Structure, tunable luminescence and energy transfer in Tb3+ and Eu3+ codoped Ba3InB9O18 phosphors

The borate Ba₃InB₉O₁₈ (BIBO) is a promising host material for phosphors. A series of Tb³⁺ and Eu³⁺ codoped Ba₃InB₉O₁₈ phosphors were synthesized. Based on the Rietveld method, structure refinement of the codoped BIBO phosphor was carried out. Then, the luminescence properties of BIBO:Tb³⁺, Eu³⁺ phosphors were extensively investigated under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation. The measured PL spectra and decay times evidenced that energy transfer occurs between the Tb³⁺ and Eu³⁺ ions. The energy-transfer mechanism from Tb³⁺ to Eu³⁺ in Ba₃InB₉O₁₈ is dominated by electric multipolar interactions, with the critical distance calculated to be 10.97 Å. The temperature sensitivity of the Tb³⁺ and Eu³⁺ codoped sample under VUV was also investigated at the low temperature range from 25 K to 298 K. The emission color could be tuned from green to the red region by adjusting the concentration of codoped ions. The results indicate that the BIBO-based phosphors are valuable candidates for applications in the display and lighting fields.

The emission colors of Ba₃InB₉O₁₈:Tb³⁺, Eu³⁺ can be adjusted from yellowish green to orange by tuning the content of Eu³⁺ ions due to the energy transfer from Tb³⁺ to Eu³⁺, thus showing a great potential for display and lighting fields applications.